Monitoring of physiological analytes

Abstract

Methods and devices are provided for measuring the concentration of target chemical analytes present in a biological system. Device configuration and/or measurement techniques are employed in order to reduce the effect of interfering species on sensor sensitivity. One important application of the invention involves a method and device for monitoring blood glucose values.

1. A method for measuring an amount or concentration of an analyte present in a biological system, said method comprising
 contacting one or more samples, comprising said analyte, with a sensing electrode;  
 obtaining a measurement signal from each sample comprising analyte using said sensing electrode that is related to analyte amount or concentration in said biological system; and  
 applying one or more processes for selectively favoring analyte-specific signal components over signal components due to interfering species, said processes selected from the group consisting of (a) selective electrochemical detection process that is performed during said obtaining, said process comprising contacting each sample with an electrochemical sensing electrode that is maintained at a potential less than about 0.6V, (b) a purge step that is performed before and/or after said obtaining, wherein said purge step substantially removes residual signal components from the sensing electrode, and (c) any combinations thereof.  
 
     
     
       2. The method of  claim 1 , wherein said contacting one or more samples with said sensing electrode to obtain the measurement signal further comprises contacting each sample with an enzyme that reacts with the analyte to provide a chemical signal that is converted at the sensing electrode to an electrical signal, wherein said electrical signal is related to analyte amount or concentration in the biological system. 
     
     
       3. The method of  claim 2 , wherein said enzyme comprises glucose oxidase, said analyte is glucose, and said chemical signal is hydrogen peroxide. 
     
     
       4. The method of  claim 1 , wherein said contacting and said obtaining are repeated for two or more samples. 
     
     
       5. The method of  claim 4 , wherein said purge step comprises operating said sensing electrode for a sufficient period of time to substantially remove residual signal components after said obtaining has been carried out. 
     
     
       6. The method of  claim 1 , wherein said one or more samples from the biological system are provided using a sampling technique selected from the group consisting of iontophoresis, sonophoresis, suction, electroporation, thermal poration, passive diffusion, use of microfine lances, use of microfine cannulas, use of subcutaneous implants, use of subcutaneous insertions, and use of laser devices. 
     
     
       7. The method of  claim 1 , wherein the analyte is glucose. 
     
     
       8. The method of  claim 1 , wherein said sensing electrode comprises a reactive surface comprising a platinum-group metal. 
     
     
       9. The method of  claim 8 , wherein said platinum-group metal is selected from the group consisting of platinum, palladium, rhodium, ruthenium, osmium, iridium, and combinations thereof. 
     
     
       10. The method of  claim 8 , wherein said contacting one or more samples with said sensing electrode to obtain the measurement signal further comprises contacting each sample with an enzyme that reacts with the analyte to provide a chemical signal that is converted at said reactive surface to an electrical signal, wherein said electrical signal is related to analyte amount or concentration in the biological system. 
     
     
       11. The method of  claim 10 , wherein said chemical signal is hydrogen peroxide. 
     
     
       12. The method of  claim 11 , wherein said electrochemical sensing electrode is maintained at a potential of less than about 0.5 volts. 
     
     
       13. The method of  claim 12 , wherein said electrochemical sensing electrode is maintained at a potential of less than about 0.42 volts. 
     
     
       14. The method of  claim 1 , wherein said biological system is a mammal. 
     
     
       15. A monitoring system for measuring an analyte present in one or more samples in a biological system, said system comprising:
 a sensing device comprising a sensing electrode, wherein said sensing electrode obtains a measurement signal from the analyte in each of said samples, and said measurement signal is specifically related to the analyte amount or concentration; and  
 one or more microprocessors in operative communication with the sensing device, wherein said one or more microprocessors comprise programming to control (i) operating said sensing device to provide said measurement signals, and (ii) applying one or more processes for selectively favoring analyte-specific signal components over signal components due to interfering species, said processes selected from the group consisting of (a) selective electrochemical detection process that is performed during said obtaining, said process comprising contacting each of said samples with an electrochemical sensing electrode that is maintained at a potential less than about 0.6V, (b) a purge step that is performed before and/or after said obtaining, wherein said step substantially removes residual signal components from the sensing electrode, and (c) any combinations thereof.  
 
     
     
       16. The monitoring system of  claim 15 , wherein the analyte is glucose. 
     
     
       17. The monitoring system of  claim 15 , wherein said monitoring system further comprises a sampling device for providing said one or more samples comprising analyte. 
     
     
       18. The monitoring system of  claim 17 , wherein said one or more microprocessors are in operative communication with said sampling device and said one or more microprocessors further comprise programming to control operating said sampling device. 
     
     
       19. The monitoring system of  claim 17 , wherein said sampling device using a sampling technique selected from the group consisting of iontophoresis, sonophoresis, suction, electroporation, thermal poration, passive diffusion, use of microfine lances, use of microfine cannulas, use of subcutaneous implants, use of subcutaneous insertions, and use of laser devices. 
     
     
       20. The monitoring system of  claim 17 , wherein the analyte is glucose. 
     
     
       21. The monitoring system of  claim 15 , wherein said sensing electrode comprises a reactive surface comprising a platinum-group metal. 
     
     
       22. The monitoring system of  claim 21 , wherein said platinum-group metal is selected from the group consisting of platinum, palladium, rhodium, ruthenium, osmium, iridium, and combinations thereof. 
     
     
       23. The monitoring system of  claim 21 , wherein said sensing device further comprises an enzyme that reacts with the analyte to provide a chemical signal that is converted at said reactive surface to an electrical signal, wherein said electrical signal is related to analyte amount or concentration in the biological system. 
     
     
       24. The monitoring system of  claim 23 , wherein said chemical signal is hydrogen peroxide. 
     
     
       25. The monitoring system of  claim 24 , wherein said electrochemical sensing electrode is maintained at a potential of less than about 0.5 volts. 
     
     
       26. The monitoring system of  claim 25 , wherein said electrochemical sensing electrode is maintained at a potential of less than about 0.42 volts. 
     
     
       27. The monitoring system of  claim 15 , wherein said biological system is a mammal.